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Asked: 2026-06-11T13:49:08+00:00

I have many queries I know should return 1 or 2 results. Should I

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I have many queries I know should return 1 or 2 results. Should I explicitly LIMIT them or just let the DB do his job?
The scenario I mean is I am WHEREing on a unique combination of keys, OR when I might have the same result many times, just do LIMIT 1 instead of using DISTINCT…

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  1. Editorial Team

    Generally speaking, you want to limit the number of rows accessed as a smaller result set runs faster.

    An excerpt from SQL Server’s* Query Performance Tuning:

    Queries should request a relatively small number of rows. For example, search engines on the Web mostly return a limited number of articles at a time, even if the search criteria returns thousands of matching articles. If the queries request a large number of rows, the increased overhead cost of a lookup makes the index less suitable.

    Alternatively, you can create a highly selective criteria:

    A filter criterion with high selectivity limits the number of rows from a table to a small result set and helps the optimizer keep the query cost low.

    *I know question is tagged as MySQL

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